"There can still be a pregnancy," he warned. "You can still get herpes. Herpes: lifelong. Other STDs, HIV -- these can all occur as the result of one poor decision."

Critics also worry that allowing Plan B for younger women will lead to more risky behavior and likely lead to more pregnancies and abortions.

"You end up with actually more sexual behavior and you end up with higher risk behavior and you end up with an increase in STDs," Greg Pfundstein, executive director of the Chiaroscuro Foundation, said.

"And you have no change in the number of pregnancies and no change in the number of abortions because people have actually changed their behavior based on their perception of risk," he added.

The bottom line: "It is a further endorsement of this philosophy of kids know best; we are going to leave it up to them," Pfundstein said.

The product will come with this label: "Not for sale to those under 15 years of age. *Proof of age required.* Not for sale where age cannot be verified."

The product will also "be packaged with a product code prompting a cashier to request and verify the customer's age," according to the FDA.

Pharmacists can accept a driver's license or permit for age verification purposes. Minors can provide other forms of identification.

"A 15-year-old can use an alternative form of ID to verify their age - for example, a passport or birth certificate," FDA spokeswoman Stephanie Yao said. "If a 15-year-old is unable to verify their age, they will not be able to purchase Plan B One-Step."

Social conservatives warn that even with the verification restrictions the over-arching message suggests there's minimal risk to unprotected sex, and this could have a reverse affect.